DNA sequence analysis identifies genetically distinguishable populations of harp seals (Pagophilus groenlandicus) in the Northwest and Northeast Atlantic

Harp seals (Pagophilus groenlandicus Erxleben, 1777) comprise three populat ions based upon whelping areas in the Greenland Sea, White Sea, and Northwe st Atlantic. The last comprises two subpopulations, one whelping in the Gul f of St. Lawrence ("Gulf") and one on the pack ice of the southern Labrador /northern Newfoundland coastal shelf ("Front"). A total of 40 female seals from the four whelping areas were collected during the 1990 and 1992 whelpi ng seasons. DNA sequence variation was examined in a 307 bp region of the m itochondrial cytochrome b gene. Eleven variable nucleotide positions define d 13 genotypes: a significant fraction of the genotypic variance (F-ST = 0. 12, or 0.09 as measured by Weir's coancestry coefficient theta) is attribut able to differentiation between Northwest and Northeast Atlantic population s. There was no significant differentiation between the two whelping areas in the Northwest Atlantic, or between the Greenland Sea and White Sea. Thes e findings suggest significant reproductive isolation exists between trans- Atlantic breeding populations.